1. FIELD OF THE INVENTION
This invention relates to connectors for joining, in current passing relationship, wires or cables fabricated from unlike metals, cooper and aluminum.
2. PRIOR ART
The selection of a current carrying metal is dependent upon the cost of that metal and its current carrying capabilities. Certain dense metals that make excellent conductors but are prohibitively expensive are silver, gold and platinum. Because of the cost of these metals, in electrical arrangement they have been limited to relay switches, or the like, and they are generally not used in current carrying wire or cable. Copper, while not as good as a conductor as silver, gold and platinum, is also an excellent conductor, and has been used for many years for electrical current carrying wire and cables. While copper is still in wide use as a current carrier in recent years with the increased scarcity and increasing cost of copper, aluminum has become more and more popular for use in current carrying wire and cable. While aluminum is not quite as good as electrical conductor as is copper, because it is generally cheaper and is lighter in weight, and because of like considerations, its use in electrical current carrying wire and cable has grown. Such growth has, in turn, accentuated a problem of joining, in current carrying arrangement unlike metals such as copper and aluminum. To provide such connection a number of devices have been proposed, but all share a common failing that, after a number of heatings, the unlike metals, because they expand at different rates will tend to move apart, thereby breaking their electrical connection. This problem is solved by the connector of the present invention.
Earlier connector configurations, such as the devices shown in a patent by Faulkner, U.S. Pat. No. 537,920, and later Reynolds and Cook Patents, U.S. Pat. Nos. 2,012,771 and 2,868,863, have recognized the need for a reliable aluminum to copper connector. These devices, however, meet that recognized need using clamp type connector arrangements wherewith one material is squeezed against another, deforming the material thereto. While this type of connector is common for joining like metals, when it is used for joining unlike metals, with the passage of time and numerous expansions and contractions of the unlike metals, due to their different expansion rates, the connector tends to loosen, possibly breaking the current path.
A more recent United States Patent issued to Prouty et al., U.S. Pat. No. 3,760,342 recognizes, as does the present invention, the desirability of aligning in parallel relationship contacts attached to ends of the different metals, such as copper and aluminum. Unlike the present invention, however, the electrical conductive medium of this connector involves electrically conductive particles arranged within an elastomer, or the like, whereby, when pressure is exerted thereagainst, the conductor particles tend to align to pass current therethrough. The present invention while it utilizes aligned contacts preferrably of different metalurgical properties for current transfer there between involves a connective fluid medium arranged between those contacts to pass current therethrough no matter what the attitude of the connector. While the patent by Prouty et al. shows contacts that extend parallel to one another, the particular arrangement of those contacts is not like those of the present invention, nor does the Prouty connector employ a conductive medium that is like that of the present invention.
It is well known that a conductive fluid medium such as mercury is useful for passing the current therethrough, such utilization being well known in the art of switches and the like. No device, within the knowledge of the inventor, has, however, utilized such conductive fluid medium in a manner like that of the present invention. Some examples of the use of a fluid conductive medium for transferring current are shown in United States Patents by Shlesinger and Appleton, U.S. Pat. Nos. 3,417,195 and 3,503,034. These connector devices, while they do employ a fluid conductive medium, do not involve an arrangement of contacts like or even similar to those of the present invention, the Appleton Patent involving contacts that are in end to end relationship rather than, as with the present invention, overlapping configuration.
Within the knowledge of the inventor there has not heretofore existed a connector that is like that of the present invention and therefore, the present invention is believed to be both novel, unique and distinct from other connectors within the knowledge of the inventor.